Field of the Invention
The invention relates to a method for gear detection in a transmission of a motor vehicle, by detecting a signal corresponding to an input rpm and a signal corresponding to an output rpm of the transmission and by forming a ratio between the two signals, wherein an engaged gear is detected from the ratio and from a known gear ratio of the transmission in various gears. The invention also relates to a circuit configuration for gear detection in a motor vehicle transmission, including a first sensor for detecting a signal corresponding to the input rpm of the transmission, a second sensor for detecting a signal corresponding to the output rpm of the transmission, and a device for forming a quotient of the output rpm to the input rpm and for detecting which gear has been engaged from the quotient and from a gear ratio of the transmission in the individual gears.
In order to improve the driving performance of motor vehicles having an internal combustion engine and a gear box, it is necessary to know whether or not a gear of the transmission, and which one, has just been engaged. Driving performance functions can be favorably varied with that information. Examples are an idling controller, an anti-bucking function, and a load impact damping of the motor vehicle power train.
In a method for controlling an automatic mechanical motor vehicle transmission system, which is known from European Patent 0 438 917 B1, the input rpm and the output rpm of the transmission are detected, and those two rpm values and the gear ratio of the particular gear which is selected are linked with one another. That will detect any instance where a gear that has been selected is not properly engaged, or if the gearshift lever pops out of engagement. However, that requires that the intended gear, or the corresponding gear ratio, be reported to a control computer by a transmission controller. The known control method does not enable ascertaining the gear ratio.